Solution-Driven Imprinting Lithography of Sol–Gel ZnO Thin Films for Liquid Crystal Display

Abstract

We present a simple and economically convenient method to fabricate nanopatterned ZnO films by imprinting lithography and use them for the layer alignment of liquid crystal (LC) displays. First, a one-dimensional nanopattern was obtained by laser interference lithography on a silicon wafer, and the silicon mold replica was transferred onto a flexible polydimethylsiloxane (PDMS) sheet for conformal patterning. The so-obtained PDMS mold was then applied on a ZnO film spin-coated on a glass substrate. During the imprinting process, the temperature was controlled from 100 to 250 °C to observe the transferring morphologies of the ZnO film; the nanopattern was successfully transferred at annealing temperatures of 200 and 250 °C because the ZnO film at the sol state filled the cavities of the PDMS nanopattern and solidified, forming a negative replica of the nanopattern. The direction of the nanopatterned ZnO film served as a guide for aligning the LC molecules on the LC surface at the centimeter scale and, due to their elastic characteristics and group behavior, propagating their directional states in the LC bulk. The resulting LC cell exhibited an enhanced electro-optical performance and high thermal endurance above 180 °C. The geometry of the alignment layer increased the electric field on the ZnO film and showed reduced threshold voltage. In addition, since flexible devices are generally based on polyimide, which imidized at around 200 °C, the relatively low annealing temperatures of our fabricated nanopatterned ZnO film allow it to be mounted on such devices without any deterioration of the underlying thermoplastic substrate. Therefore, nanopatterned ZnO has a considerable potential for advanced LC displays.

Progress in the Synthesis and Application of Transparent Conducting Film of AZO (ZnO:Al)

“…In addition, the excellent optoelectronic properties of AZO films make them widely used in other fields, such as liquid crystal displays [ 80 , 81 , 82 ], anti-static films [ 83 ], thermal mirrors [ 84 ], transparent surface heaters [ 85 , 86 ], and infrared stealth materials [ 87 , 88 , 89 ], radar shielding protection [ 90 ], glucose sensing [ 91 ], biosensors [ 92 ], antibacterial applications [ 93 ], etc. The AZO thin-film material is non-toxic, has a simple preparation process, doping that is easy to achieve, and cheap raw materials that are easy to obtain; therefore, it has great development potential.…”

Mechanism of Imprinting Process in the Ni-P Metallic Glass Films: A Molecular Dynamics Study

“…Fabrication of engineering components at micro/nanoscale is one of the huge challenges in the high-tech industries [1][2][3]. To overcome this issue, nanoimprinting lithography (NIL) has been proposed as a novel technique in which the fabricated patterns and components are the potential candidates for application in optical devices, micro-integration systems, nanomold production, and biological devices [4,5]. In this method, a mechanical deformation process is conducted to transfer the pattern onto the metallic flms by an imprinting-release procedure [6][7][8].…”